Point-to-plate gas-filled rectifier



July 30, 1929. H. E. METCALF POINT TO PLATE GAS FILLED RECTIFIER I Filed March 23, 1927 I N VE TOR Patented July so, 1929.

UNITED STATES 1,722,588 PATENT OFFICE.

HERBERT E. METCALF, OF SAN LEANDRO, CALIFORNIA, ASSIGNOR TO THE MAGNA- VOX COMPANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF ARIZONA.

POINT-TO-PLATE GAS-FILLED RECTIFIER.

App1ieation filed March 23, 1927. Serial No. 177,592.

This invention relates to a vpoint-to-plate type gas filled rectifier and especially to the full wave type.

The object of the present invention is to generally improve and simplify the construction and operation of rectifiers of the character described; to provide a structure whereby leakage of alternating current between the oints or electrodes of a full wave point-toplate gas filled rectifier is reduced to a minimum; to provide a structure which will prevent heating of the points or electrodes due to alternating current leakage; and further to provide a structure which will allow higher voltages to be employed with less heating of the points or electrodes. The invention is shown by way of illustration in the accompanying drawings in which Fig. 1 shows one form of rectifier,

Fig. 2 shows a modification thereof,

Fig. 3 is a diagrammatic view illustrating the manner of connecting the two electrodes and the plate to a transformer.

A full wave gas filled rectifier consists briefly of two points or electrodes surrounded by a plate. The two electrodes are anodes while the plate serves as a cathode. The plate together with the electrodes is placed within a tube and this is evacuated and finally filled with helium or neon gas at a pressure of 1 to 5 millimeters of mercury.

\Vhen used as a full wave rectifier, the cathode or plate is connected to the center tap of the secondary of a transformer as shown in Fig. 3 and the two points or anodes to the ends. Thus it is that while there may be a potential of one unit between each electrode and the plate, there is a drop of two units between the points. For instance, if 500 volts are employed between each point and plate, the points are subjected to a difference of potential of 1000 volts. As both points are usually the same size, a current will pass between them and due to the hi h voltage a destructive arc may easily be started and ruin the rectifier.

The present the two electrodes very close together and in parallelism, taking advantage of the fact that when two electrodes are positioned close enough in a conducting gas, no current will pass between them because impact ionization cannot occur in the limited space. In actual practice referring to Fig. 1, the lower ends of the points or electrodes are glass enclosed as indicated at 2 and bent over and paralleled scope of the appended claims;

invention consists in placingwith not over 1/32 of an inch spacing be tween them. Measurements show that when this is done practically all current flow between two points ceases and the heating due to said current leakage or flow disappears. In the type of structure shown in Fig. 1, a cylindrical type of plate is employed as indicated at 3, the points or electrodes being bent at right angles and paralleled with relation to each other as indicated at 4. In the type of structure shown in Fig. 2. the lower ends of the electrodes or points are also enclosed in glass as indicated at 2 A lavite block or the like such as indicated at 5 having guide holes therein is then passed over the upper ends of the electrodes and they are bent inwardly to assume a vertical closely spaced paralleled position as indicated at 6. A cylindrical-shaped plate may be employed as shown in Fig. 1 but a disc-shaped plate may also be employed as indicated at 7 in Figure 2. this being supported above the upper ends of the electrodes 6 by supporting wires or rods as indicated at 8, one of the rods at the same time forming one of the terminal connections for the plate. In either type of construction shown in Figs. 1 or 2 it will be understood that the entire assembly is inserted in the tube indicated at 9 and that this is then thoroughly exhausted and finally filled with an inert gas such as helium, neon or the like, the tube being finally sealed off when it is ready for use. A rectifying tube constructed in the manner described, reduces alternating current leakage between the electrodes to a minimum; it prevents arc action between the electrodes and it furthermore reduces heating to a minimum.

While certain features of the present invention are more or less specifically described and indicated, I wish it understood that various changes may be resorted to within the similarly, that the materials and finish of the several parts employed may be such as the manufacturer may dictate or varying conditions or uses may demand.

Having thus I claim and is 1. In a full wave gaseous rectifier of the point-to-plate type, two linear electrodes constituting the points, said electrodes being placed parallel throughout their exposed area and interspaced approximately 1/32 of an described my invention, what desire to claim by Letters Patent 2 1,722,:ssa

inch and a plate electrode cooperating therebent substantially at right angles to assume with. a horizontal position, said bent portions of 10 2. In a rectifier of the character described, the anodes being parallel and closely intera tube, aneck in the lower portion of the tube, spaced and a cylindrical-shaped cathode 5 a pair of rod-like anodes sealed in the neck mounted within the tube and surrounding the of the tube and projecting into the tube, a anodes.

pair of glass tubes surrounding the lower ends of the rod-like anodes, each anode being HERBERT E. METCALF. 

